<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>判断空气污染程度</title>
</head>
<body>
    <script>
        var a =290;
        if(a>=0 && a<=100){
            document.write("API:"+a+"空气污染状况：良好")
        }else if(a>=101 && a<=200){
            document.write("API:"+a+"空气污染状况：轻度污染")
        }else if(a>=201 && a<300){
            document.write("API:"+a+"空气污染状况：中度污染")
        }else{
            document.write("API:"+a+"空气污染状况：重度污染")
        }
    </script>
</body>
</html>